Research was conducted in New Hampshire during Fall 1995 and Spring 1996 to determine a planting schedule, rowcover type, application time, and plastic mulch type to be used in adapting the annual hill strawberry production system to New England. Treatments in Fall 1995 included two planting dates, three mulch types, and four rowcover modifications. Yields did not differ statistically between a 18 Aug. and 1 Sept. planting date or among plastic mulches. Typar 518 floating rowcovers significantly increased branch crowns, and early and total fruit yield compared to hay mulch applied for winter protection. Research was initiated in Fall 1996 to determine the effect of runner production on yield. Plug plants (50 vs. 24 tray) were treated with different day lengths and temperatures and planted in the field on 26 Aug. or 9 Sept. All plants were covered with Typar 518 on 4 Oct. 1996. Larger, late-planted plugs treated with cool, short days produced no runners in Fall 1996 and increased branch crowns and total yield in Spring 1997. Plants set out in Fall 1995 were evaluated for 2nd year production with or without runner pruning and four rowcover treatments in Fall 1996. Runner pruning did not significantly increase total yields, but resulted in earlier fruit harvesting in Spring 1997. Typar 518 applied 4 Oct. resulted in the greatest yield of any rowcover treatment.
Charles D. Bornt, J. Brent Loy, William G. Lord, and Otho S. Wells
Jeffery K. Iles
A survey was conducted to identify and characterize the effectiveness of overwintering methods used to protect container-grown herbaceous perennials in USDA hardiness zones 3 through 8. Survey questionnaires were sent by first-class mail on 20 Aug. 1996 to 634 firms involved in growing and/or selling container-grown herbaceous perennials identified from the Perennial Plant Association Membership Directory. Completed questionnaires were received from 293 individuals (46.2% response rate) in 38 states, the District of Columbia, and six Canadian provinces. Survey participants reported using several overwintering methods: structureless systems (71.0%), polyhouses (52.9%), polyhouses with inflated double polyethylene covers (30.7%), and low-profile polyhuts (12.3%). Over three-fourths of the respondents (78.8%) said their winter protection methods resulted in minimal to no plant loss (0-10%). Only 53 respondents (18.1%) reported losses >10%. The most frequently cited reason for plant loss across all hardiness zones was excessive moisture inside the overwintering environment (50.2%). Equal percentages (33.4%) indicated low temperatures and damage from animals as the next most likely factors responsible for plant loss. Respondents identified, in descending order, Iris, Delphinium, Lavandula, Papaver, and Lupinus as the five genera most difficult to overwinter.
Carolyn DeMoranville, Anne Averill, and Martha Averill
In commercial cranberry (Vaccinium macrocarpon Ait.) production, flooding is used as a cultural practice for harvest and for winter protection. In addition, after the withdrawal of the winter flood, cranberry bogs may be reflooded in the spring, a practice known as holding “late water” (LW). This practice was used by early cranberry growers in Massachusetts to avoid spring frost and to promote keeping quality in the harvested fruit. Recently, LW has been “rediscovered” as a cultural tool with the potential for reducing inputs of chemical pesticides and fertilizers. We have begun to document the effects of LW on pest populations and on cranberry plants to provide growers with a solid basis for deciding whether to use this cultural practice. In 1993, 11 LW bogs were studied and compared to control bogs. All of the bogs showed acceptable levels of insect and disease damage on the fruit at harvest. The average number of pesticide applications for the LW bogs vs. controls was 0.9 vs. 2.6 for insecticides and 1.3 vs. 2.8 for fungicides.
William F. Hayslett, P. R. Thangudu, and Sabrina Shaw
A field study was conducted at Tennessee State University's research station to evaluate the effect of hardwood bark mulch on the winter survival of garden mums. A randomized complete block design was used. Cultivars used were adorn, encore, grandchild, jackpot, legend, minnautumn, minnwhite and triump. At the end of the flowering season the tops were removed leaving a four inch stubble in the mulch. The number of mum plants that resumed growth the following spring were counted for each cultivar. There was a difference in the winter survival of the different cultivars as well as a significant difference in the mulch treated and the control. Grandchild and jackpot were most cold hardy followed by encore, minnwhite, minnautumn, triump, legend, and adorn. Grandchild and jackpot with four inches of hardwood bark mulch had an 88 percent survival while the control had a 44 percent survival. Adorn. had a 51 percent survival with four inches of mulch and a 20 percent survival in the control. This data shows that hardwood bark mulch holds a great potential for providing excellent winter protection for garden mums.
Gregory E. Welbaum
The globe artichoke (Cynara scolymus L.) is usually propagated vegetatively because plants grown from seed lack uniformity. Furthermore, in much of the United States, only a small percentage of plants grown from seed flower during the first season due to insufficient chilling for vernalization. Artichokes cannot be grown reliably as perennials without winter protection where temperatures are consistently below -10C. The new cultivars Imperial Star (IS) and Talpiot (TP) reportedly produce uniform plants from seed and a high percentage of flower heads (capitulum) the first year with minimal chilling. `Imperial Star' and TP were compared with the standard seed-propagated cultivars `Green Globe Improved' (GG) and `Grande Buerre' (GB). Plants of each cultivar were tested over a 3-year period in Blacksburg, Va., or for 1year in three other locations. Essentially all IS and GG plants flowered after receiving 1356 h of chilling at <10C. With 205 h of chilling, 83% of IS plants flowered compared to 25% for GG. No TP or GB plants flowered after receiving as much as 528 h of chilling. In the mountains of western Virginia, only IS plants established in the field in early May received sufficient chilling to produce flower heads during the late summer and early fall. June transplants did not flower because sufficient chilling was not obtained for vernalization. In warmer areas of central and eastern Virginia, fall establishment for spring harvest may yield a higher percentage of flowering plants compared to spring planting and summer harvest.
Michelle R. Botelho and Justine E. Vanden Heuvel
Cranberry production involves the use of flooding for several purposes during the growing season, including pest control, winter protection, and harvest. The effect of the dissolved oxygen concentration in floodwater on carbohydrate concentration of uprights and roots during flooding was investigated using potted `Stevens' cranberry (Vaccinium macrocarpon Ait.) vines. Pots were placed in large bins filled with water to simulate a spring pest control flood (called late water) over a 21-day period. Two treatments were applied: oxygenated and nonoxygenated (control). Uprights and roots were collected every 3 days and prepared for HPLC analysis to quantify nonstructural carbohydrate concentration. Soluble sugar (sucrose, glucose, and fructose) and starch concentration, as well as total nonstructural carbohydrate (TNSC) concentration, decreased over the 3-week period in uprights but not roots regardless of treatment. Interestingly, the sucrose, glucose, fructose, and starch concentrations of uprights in the oxygenated treatment were lower than those of uprights in the control treatment throughout the experiment. This research indicates that vines in flooded bogs demonstrate a net carbon loss, resulting in reduced carbohydrate concentration available for growth and fruit production.
Martin P.N. Gent
Strawberry (Fragaria × ananassa Duchesn.) cultivars differ in response to removal date of row covers when they are used for winter protection and to accelerate fruit development and production. In 1986-87 and 1987-88, eight cultivars were overwintered under either spun-bonded polypropylene row cover or under straw. The straw was removed from control plots in late March. Row covers were removed on four dates beginning in late March and separated by about 2-week intervals. The time of flowering, fruit set, and fruit ripening was advanced in direct relation to the time that row covers remained over plants in spring. The differences in time of fruit ripening were less than those of time of flowering, however. The mid-harvest date was advanced as much as 8 days for `Earlidawn' and `Midway', but only 4 days for `Redchief' and `Scott'. Weight per fruit and percentage of marketable fruit were reduced when plants remained under row cover until mid-May. This effect was most noticeable for `Earlidawn', `Guardian', and `Redchief'. The fruit quality of `Midway' and `Jerseybelle' was not significantly affected by date of row cover removal. These cultivar-specific responses were probably not related to the stage of fruit development when row covers were removed, as both early and late-flowering cultivars were sensitive (and insensitive) to the date of row cover removal.
Laura G. Jull*
A hardy shrub rose evaluation trial was planted at three locations in Wisconsin representing U.S.D.A. cold hardiness zones 3, 4, and 5. There were nine replications of each of the 20 different, new or underused rose cultivars located at each location. The roses were then evaluated monthly (May-Nov.) for three years. Monthly data were taken and parameters included: plant height, width, flowers (color, size, amount, duration), insect injury, disease susceptibility, hips (production, size, and color in fall), and amount of winter dieback in spring. Pesticides and winter protection were not used in the trial to properly evaluate for pest resistance and cold hardiness. Pest resistance for roses varied among the cultivars. `Marie-Victorin' was the most severely infected rose by insects. Blackspot and anthracnose were severe (>60% of plant infected) on `Robusta', Red FairyTM, Kaleidoscope™, Cambridge™, and Madison™. Flower amount and continuous bloom occurred on Carefree Delight™, Cambridge™, Madison™, Knockout™, Fire Meidiland™, Mystic Meidiland™, and Red Fairy™. Hip production occurred on many of the cultivars, however, only Carefree Beauty™, `Marie-Victorin', and Mystic Meidiland™ produced colorful orange-red hips. Winter hardiness also varied between the cultivars.
Angela M. O'Callaghan
Garlic (Allium sativum L.) has been cultivated in much of the world for millennia. Little scientific research, however, has focused on improving cultural conditions for production in the temperate regions of the northeastern United States, where garlic is gaining importance as a horticultural crop. To study the effectiveness of wheat straw (Triticum aestivum) mulch on garlic, experiments were conducted at the Cornell Univ. research facilities in East Ithaca, N.Y., during the 1993–94 (year 1) and 1994–95 (year 2) growing seasons and at the Homer C. Thompson Vegetable Research Farm, Freeville, N.Y., during the 1994–95 growing season. Two clones, one bolting and one nonbolting, were studied in year 1, and four varieties, three bolting and one non bolting, in year 2. All were fall-planted (mid-October), and mulch treatments were covered with wheat straw early in the following December. Control plots were not covered. The mulch either remained on the crop throughout the growing season or was removed early in the spring to expedite soil warming. This is the common practice among growers who use mulch only for winter protection. The presence of mulch during the winter increased the survival rate. Soil temperatures under the wheat straw were significantly lower during the summer than soil temperatures in unmulched plots, which could have contributed to the increase found in the yield and average bulb size of several of the cultivars. Maintaining the mulch through the entire growing season reduced weed pressure >30%. We found no significant increase in the amount of basal fungal infection. The results indicate that using straw mulch can improve garlic produced in the northeastern United States.
Production and use of sweet olive (Osmanthus armatus), fragrant tea olive (O. fragrans), holly tea olive (O. heterophyllus), and fortune’s osmanthus (O. xfortunei) as a landscape plant is currently limited to U.S. Department of Agriculture (USDA) Hardiness Zones 7 to 10, and nursery growers wish to extend the range of these species into colder climates. To provide recommendations to growers and landscapers and inform breeding efforts for cold-hardiness improvement, a replicated trial was conducted in a USDA Hardiness Zone 6b/7a transition zone. Fifteen cultivars and two unnamed accessions representing four species were evaluated for growth, stem necrosis, and flowering in a pot-in-pot production system from 2015 to 2017. One-half of the plants in each cultivar were moved to winter protection each November and returned to the field each May. There were significant differences in growth and cold-hardiness among cultivars. Percent increase in the growth index after three growing seasons for winter-exposed accessions of sweet olive, fortune’s osmanthus, fragrant tea olive, and holly tea olive averaged 867%, 1175%, 155%, and 6361%, respectively. Percent stem necrosis in May 2017 for sweet olive, fortune’s osmanthus, fragrant tea olive, and holly tea olive averaged 1.1%, 2.7%, 44.8%, and 20.2%, respectively. The most cold-tolerant accessions based on stem necrosis and growth index of winter-exposed plants were ‘Kaori Hime’, ‘Hariyama’, ‘Shien’, ‘Head-Lee Fastigate’, and ‘Rotundifulius’ holly tea olive, ‘San Jose’ fortune’s osmanthus, and ‘Longwood’ sweet olive. Of these cultivars, Kaori Hime, San Jose, and Longwood flowered under winter-exposed conditions. All fragrant tea olive cultivars were damaged by winter exposure. ‘Fodingzhu’ was the only fragrant tea olive cultivar that flowered each year under winter-exposed conditions. Evaluation and breeding efforts are continuing to extend the range for production and growth of this genus.